Help me please with these basic questions about the role of the Wireless Access Controller (AC).
Suppose the Access Controller and Access Point are connected via IP:
- Wireless Frames sent from AP to AC; include the original MAC header (of the wireless path)? In case Yes, is there a Cisco AC able to bridge the WLAN and the LAN it is connected (meaning it outputs Ethernet frames as if they were originated by Mobile Stations).
- Is the AC necessarily the default gateway for the mobile stations? I suppose not. But can it be made the default gateway?
Can the Cisco AC work as a DHCP relay?
The AP creates a tunnel to the controller. All IP traffic from the AP to the controller will have source address of the AP and dest IP to the AP Manager interface on the controller. The wireless client traffic is encapsulated inside this tunnel. When it hits the controller the CAPWAP is removed leaving the original packet from the client to be sent to the LAN by the controller.
The controller should not be the default gateway for the wireless clients because it is not a router. Think of it as an appliance that converts wireless traffic into wired.
Normally the controller acts as a DHCP proxy. Once the client has joined a WLAN, the controller sends DHCP packets to the the DHCP server on behalf of the clients like the ip helper address normally configured on the router for wired clients. Alternatively you can configure the controller to act as the DHCP server for wireless clients.